Section Menu

Seawater Greenhouse Ltd

Sector:           Design & manufacturing
Employees:      3
Location:         London

The big idea :-  to use the heat from sunlight to distil seawater to irrigate crops and enable them to grow in cooler conditions.

What they do

Established in 2000, Seawater Greenhouse Ltd has developed a process that provides fresh water and cooling in greenhouses in order to provide an economic and sustainable means of cultivating high quality crops, year round, in hot, arid coastal regions.

The greenhouses integrate cooling and solar desalination and yet use very little electrical power as most of the thermodynamic work of distillation is performed by the sun and the wind. A 1000m2 greenhouse requires less than 2kW for the pumps and fans and yet removes 800kW of heat, cooling the ventilation air and distilling sufficient fresh water for the crops.

The challenge

… was to provide a low cost and sustainable means of producing fresh water and crops in hot, arid regions.
As Seawater Greenhouse CEO Charlie Paton says, 'The availability of fresh water is threatened in many parts of the world by population growth and other factors. A third of the planet is forecast by the UN to face water shortages by 2025. With agriculture accounting for some 70% of all water used, the water crisis is closely linked to food production and economic development.'

Present methods of supplying irrigation water in arid regions can lead to conflict. They include over-abstraction of ground water, diversion of water from other regions, and energy-intensive desalination. None of these methods are sustainable in the long term. In many, if not most, countries of the world, groundwater is now extracted faster than it is replenished by rainfall, and wells are continuously made deeper. This causes increased contamination, especially with salts.

Charlie Paton agrees. 'Conventional desalination is generally an option only to countries with abundant fossil fuel reserves. The Seawater Greenhouse by contrast is driven by solar energy, and works best in hot, sunny regions.'

The solution

Solar distillation of seawater and evaporative cooling are not new ideas, but combining them in one productive structure, to optimise crop cultivation, is a novel concept. 

The greenhouses work by providing optimum conditions for rapid plant growth. Plant growth is driven by sunlight - the more light, the more growth. However, plants use only a small fraction of the total solar radiation they are exposed to for the photosynthesis necessary for growth and the high temperatures which accompany plentiful sunlight actually hinder the process, forcing plants to transpire too much water.

The Seawater Greenhouse takes the heat out of the sunlight, allowing the plants to grow in cooler, yet high light conditions and uses the heat to distil fresh water from seawater.

Issues arising

As most, if not all the greenhouses, will be located in sunny and arid locations, it was necessary to decide what to build and ship from the UK and what to allow local contractors to build from detailed plans and specifications supplied by the company, as frames and glass are very bulky and fragile giving rise to high shipping costs if the entire package was made in the UK.

The decision was made to outsource all frames and installations and have them fabricated and installed by approved suppliers, preferably those situated as close to the chosen site as possible to minimize transport and associated costs.

Only the bespoke items such as control systems and plastic heat exchangers, which are unique to each application, are designed and manufactured in the UK.

The outcome

The growth in demand for water and increasing shortages of supply will continue into the future and agriculture, with a high demand for water, will be a major pressure point.

The Seawater Greenhouse will help to address this crucial problem in a cost-efficient and sustainable way, saving scarce water supplies for human and industrial use.

To date, three complete installations have been supplied and another three are at the planning stage.

No doubt more will follow. As Marco Goldschmied, President of the Royal Institute of British Architects said in 2000, 'The Seawater Greenhouse is a truly original idea which has the potential to impact on the lives of millions of people living in water-starved areas around the world.'

What could you do?

Environmental issues, whether reducing carbon emissions or utilising water more efficiently, will become major drivers for innovative solutions, products and services in the years ahead. Could you enter this exciting new market? Visit http://www.envirowise.gov.uk to find out more.

Innovation Exchange

Seawater Greenhouse website: http://www.seawatergreenhouse.com

Back to Case Studies home page